In an air conditioner in which refrigerant circulates to perform a vapor compression refrigeration cycle, electrical circuits such as inverter circuits are mounted in order to control an operating state of an electric motor of a compressor. A power device generating high-temperature heat has been generally used for such an inverter circuit, and a unit configured to cool the power device is provided in a conventional air conditioner so that the temperature of the power device does not exceed a temperature at which the power device is operable. An example of such a cooling unit includes, e.g., a unit configured to cool a power device by refrigerant used for a refrigeration cycle (see, e.g., Patent Document 1). In an air conditioner of Patent Document 1, a refrigerant path through which the refrigerant used for the refrigeration cycle flows is provided in a refrigerant jacket (heat sink in Patent Document 1). In addition, the power device (giant transistor in Patent Document 1) is fixed to the refrigerant jacket, and the refrigerant jacket is accommodated in an electric component box.